1. Field of Invention
The present invention generally relates to machines for dispensing an accurate count of unit objects from a bulk storage location. More particularly, the invention concerns a vacuum operated system for accurately dispensing medicine or other pharmaceutical articles to a user such as a nurse, where the number or type of articles to be dispensed is selected by the user in advance, and where each article is dispensed individually from bulk storage under computer control.
2. Description of Related Art
In recent years, a number of systems have been designed to deliver medicine at locations such as nursing stations in hospitals. By providing an inventory of medicine at such locations, these systems have attempted to reduce the need for nurses or pharmacy personnel to repeatedly travel between the nursing station and the pharmacy to acquire medicine. These systems also seek to help management of medicine and control inventory more easily. Some examples of these systems include the Meditrol machine (made by Meditrol), the SureMed and ATC 212 machines (made by Baxter), and the Pyxis product line (made by Pyxis).
Although these systems have been adequate for their intended purposes in many respects, they are limited in other ways. Some of these systems store the articles to be dispensed in a small bin, and they provide a user with access to the articles in the bin by opening the bin in one way or another. One disadvantage of such systems is that monitoring the number of articles removed from a bin by a user is difficult, if not impossible, without relying on each user to honestly report the number of articles s/he removed.
Other of these systems approach this difficulty by providing a single "unit dose" package per compartment. "Unit dose" refers to packages containing a single item of medicine, typically bearing a printed identification of the medicine and a lot number. Unit dose packages may be undesirable to some, due to their significantly higher cost compared to bulk packages. Also, with one unit dose per bin, the packages must be loaded one at a time, thereby increasing the labor required to fill the bins.
As a result of these limitations, there has been a need for a system capable of individually retrieving items from a batch of like items stored in a bottle, bin, jar, or other bulk container, and making the retrieved items available to a user. One approach to this problem uses robotic equipment to manipulate a distinctive bottle, and drop a desired amount of medicine from the bottle into a packaging system for a patient's current or daily dose of medication. A potential problem with the robotic device that uses a distinctive bottle is that, for each bottle of medicine, a backup bottle must be accessible to avoid delays after the first bottle is emptied. However, the backup bottle cannot be "piggybacked" with the primary bottle due to the structure of the robotic device, and also due to the requirement that medications produced in different lots may not be mixed; accordingly, two spaces must be allocated for each different medicine provided by the device if stock-outs are to be avoided. This reduces the potential variety of medicines provided by the robotic device. Some might also consider the robotic machine to be limited because its bottles cannot be added to or "topped off," and therefore each bottle must be used until it is completely empty, and then manually replaced. As a result, the service schedule for the device is not as predictable as some might prefer, since each bottle must be serviced when its contents are depleted.
In contrast to the above-mentioned robotic system, other robotic systems have used vacuum arrangements to pick up small articles aided by a vision system of some type. For example, Seiko has employed a vacuum pick-up to lift watch hands from unordered batches to assist in assembling watches in an industrial environment. The Seiko system utilizes a vision system to control positioning of the vacuum pick-up. Although the Seiko system may be suitable for some applications, its benefits are limited when considered for dispensing medicine. For instance, the Seiko system only provides a single probe tip for vacuum pick-up of all parts. However, in dispensing medicine, the use of a probe tip must be limited to one specific type of medicine, to eliminate any possibility of cross-contamination from other medicines. The Seiko approach is also limited for dispensing medicine since a vision system capable of recognizing the wide variety of sizes, colors, and shapes of medicine would be unduly complicated. Moreover, the cost, size, and noise of the Seiko system is not appropriate for a hospital environment.